This invention relates to an improvement in a substantially thin keyboard for use in a variety of small sized electrical apparatus.
A conventional low profile keyboard is designed to short or bridge a pair of stationary key contacts upon actuation of their corresponding electrically conductive rubber movable contact from above. The unique indicia printed on a key actuator cannot be changed unless the indicia is reprinted. In order to afford a plurality of functions to one of keys on the keyboard, a particular key is provided for distinction purposes. As an alternative, the key actuators are eliminated and an indicia carrying sheet is disposed immediately above all of electrically conductive rubber contacts. In this case, one or more distinction keys are further needed for multi-function keys as described previously.
For large size keyboards for use in computer terminals, etc., rather than the above discussed small sized or low profile keyboard for credit card size calculators and so forth, there have been suggested various approaches to change the indicium or marking, i.e., the function of the same key by the use of mechanical or electrical means. Such approaches require the keys of the device large in size and complicated in construction and the indicia or markings on the respective keys are difficult to read.